NEW FORECAST PUTS PEAK GLOBAL POPULATION AT 9.7-B IN 2064

The world’s population may never grow as large as many had previously assumed. In a new paper, researchers at the Institute of Health Metrics and Evaluation (IHME) at the University of Washington project that the global population will top out in 2064 and then fall steadily, The Economist today noted in July 17, 2020 issue. 

Current estimates by the UN’s Population Division reckon it will continue to grow until at least 2100. As a result, the IHME estimates a total population of 8.9 billion in 2100 while the UN places the number at about 10.9 billion. The huge discrepancy is largely accounted for by differing views on two issues. First, the IHME study’s central scenario assumes that improvements in access to education and contraceptives in sub-Saharan Africa—and a concomitant fall in fertility—will result in a population there of just under 3.1 billion in 2100, compared with 3.8 billion in the UN study. Accounting for mortality, this means 890 million fewer African births on a cumulative basis in the remainder of the century. However, even the IHME’s conservative projections still have sub-Saharan Africa as the only continent with a growing population by the end of the century. 

Other demographers have also argued that better education could cause the global population to peak before the end of the century. Last year, The Economist reported on projections by Wolfgang Lutz, a demographer at the International Institute for Applied Systems Analysis in Austria. If recent progress in education in sub-Saharan Africa was maintained, estimated Lutz, the world’s population would peak at 9.4 billion in 2075 and decline to 8.9 billion by 2100 (as IHME also estimates). Brisker progress would imply an earlier peak, at 9 billion and a fall to 7 billion by the end of the century. 

The second reason for the discrepancy between the IHME’s and the UN’s figures is that the former is more conservative about what will happen to populations when fertility rates fall below the replacement level of 2.1 births per woman. The UN assumes that in many countries with low rates, such as Taiwan, where the fertility rate is just over 1, they will increase again—not all the way to 2.1, but to around 1.75. The IHME believes that 1.4 is a more likely outcome. The difference yields a substantial gap in population projections.